多粘类芽孢杆菌Cp-S316抗真菌活性物质的提取及其部分性质研究

多粘类芽孢杆菌Cp-S316对动植物真菌、细菌病原物具有广谱抗性,为研究抗真菌活性物质的化学结构、理化性质并探讨其工业化生产的可行性,研究了大孔吸附树脂对多粘类孢杆菌Cp-S316产生的抗真菌活性物质的吸附、解吸性能,筛选出其最佳解吸剂,并测定了抗真菌活性物质的部分性质.结果表明,大孔吸附树脂X-5对抗真菌活性物质的吸附及解吸性能最好,其饱和吸附量为5.36×104 μg·g^-1,其最佳解吸剂为0.01 mol·L^-1 HCl-70%乙醇,以解吸剂∶树脂=2∶1（v∶m）进行静态解吸,解吸率达93.28%.该活性物质对热、紫外线稳定,对胰蛋白酶、蛋白酶K有一定的耐受性,对氯仿部分敏感,对酸稳定,对碱敏感.抗真菌活性物质提取方便、理化性质稳定,显示了一定的应用和开发前景.     

K营养对烤烟叶片中几种抗性物质及野火病发生的影响

 通过对云南中部地区不同生长状况、不同发病程度的34个烤烟样品的钾、总酚、类黄酮含量分析和田间病害调查，结果表明：烟叶一般K含量为1%～4%，K含量高于4%的较少，无低于1%的样品；在K含量为2%～4%的范围内，随钾含量的增加，总酚、类黄酮含量提高，过氧化物酶活性增强，烤烟野火病病情逐渐减轻； K含量＞4%及<2%时，总酚、类黄酮含量降低，过氧化物酶活性减弱，野火病发病严重。     

基于Akt信号通路探究益生菌对绵羊蛋白质合成及风味的影响

为基于Akt信号通路探究日粮添加益生菌对绵羊蛋白质合成及风味的影响,选取对照组(基础日粮)和益生菌组(基础日粮中补充丁酸梭菌,5 g/(只·d),活菌数为5.0×10⁸CFU/g)杜泊×小尾寒羊杂一代母羊各9只,将其屠宰后取背最长肌测定肌肉重量、风味物质相对含量、肌纤维组织学形态和蛋白质合成代谢相关酶活及基因表达情况。结果表明：与对照组相比,益生菌组绵羊背最长肌质量显著增大(P<0.05),肌纤维直径及横截面积极显著增大(P<0.01),肌肉中支链氨基酸转氨酶(branched chain aminotransferase,BCAT)及支链α-酮酸脱氢酶(branched-chain α-keto acid dehydrogenase,BCKDH)活性显著升高(P<0.05);益生菌组胰岛素样生长因子-1(insulin-like growth factor 1,IGF-1)、蛋白激酶B(protein kinase B,Akt1)、哺乳动物雷帕霉素靶蛋白(mammalian target of rapamycin,mTOR)、p70核糖体蛋白S...     

Silicon effects on aluminum toxicity to mungbean seedling growth

The effects of silicon (Si) on the toxicity of aluminum (Al) to mungbean (Phaseolus aureus Roxb.) seedlings were studied in a growth chamber. Mungbean seedlings were grown in a nutrient solution with combinations of three concentrations of Si (0,1, and 10 mM) and three concentrations of Al (0, 2, and 5 mM) in randomized completely block design experiments for 16 days. Silicon at 1 mM in the solution decreased root length, fresh and dry weights, and chlorophyll content, and showed no significant effect on epicotyl length and seedling height, and protein contents of shoots or roots in mungbean seedling under no Al stress. But, Si at 10 mM showed marked toxic effects on mungbean seedling growth and increased protein contents of the shoots or roots. In contrast, under 2 mM Al stress, Si addition at 1 mM had significant increasing effect on root length, fresh and dry weights, and chlorophyll content. It also had decreasing effect on protein contents of the shoots or roots, and had no effect on epicotyl length and seedling height. Silicon addition at 10 mM showed no effect on morphological and physiological measurements of mungbean seedling. However, Si at 1 mM added to solution only increased seedling height, epicotyl length, fresh weight, and chlorophyll content, but decreased dry weight and protein content of the roots under 5 mM Al stress, significantly. Silicon addition at 10 mM showed similar toxic effects on mungbean seedling growth under 5 mM Al stress to that under no Al stress.     

Fate of humic acids isolated from natural humic substances

Composition of humic acids (HA) is a function of plant-derived inputs, degradation processes regulated by microorganisms, organo-mineral interactions and age. Characterization of different origin humic substances is important for evaluation of their contribution to stabile and labile carbon pool in the environment. The relative abundance of chemical components in HA isolated from soils, compost, commercial lignohumates, alginite, acadiane and lignite was studied with aim to quantify content of important biomarkers such as amino acid, lipids and polyphenols. HA were considered as a heterogeneous complex and high concentration of peptides, polyphenols and lipids was determined in acadian-HA to compare with soil-HA. Compost-HA contained much more amino acids to compare with soil-HA samples. Alginite-HA and lignite-HA were similar in biomarkers content to soil-HA. Fourier transform infrared spectroscopy confirmed that chemical composition and functional groups content differs with the origin, humification degree and the age of studied samples. Soil-HA are typically composed of a variety of ?OH, COOH?, C–O, C–H₂, (aliphatic and aromatic) groups, quinines, lignin fragments, polysaccharide, monosaccharide and proteins fragments, which are linked together by ?O?, ?NH?, ?H=, >C=O, metal ions and –S? groups. ¹³C NMR spectroscopy showed that aromatic carbon content was the highest in lignite-HA and soil-HA.     

Mechanisms of plant growth stimulation by humic substances: The role of organo-iron complexes

Abstract

Stimulatory effects of humic substances (HS) on plant growth have been observed and widely documented. Studies have often shown positive effects on seed germination, root initiation and total plant biomass. The consistency of these observations has been uncertain, predominantly due to the lack of understanding of the plant growth promotion mechanism. Often these effects have been attributed to a direct effect of plant growth hormones; whereas in other instances the term “hormone-like activity” has been used to describe the plant growth stimulation (Chen and Aviad, Humic Substances in Soil and Crop Sciences: Selected Readings, American Society of Agronomy, Soil Science Society of America, 1990; Nardi et al., Humic Substances in Terrestrial Ecosystems, Elsevier Science B.V., 1996). Yet, investigators have been unable to prove that plant growth regulators are present in HS preparations, or the evidence provided remains unconvincing. An alternative hypothesis suggesting that growth enhancement of plants grown in nutrient solution (NS) containing HS is the result of improved micronutrient availability, Fe in particular, has been postulated and tested in the present study. Nutrient solutions containing N, P, K, Ca, Mg, S, B, Mo, Cu, Mn, Zn, and Fe at concentrations considered to be optimal for plant growth were tested for solubility of the Fe, Zn, and Mn, 7 days after preparation. In addition to control solutions at pH values of 5, 6, 7, and 7.5, 0 to 200 mg L^?1 of leonardite humic acid (HA) were added to the solutions and they were tested for Fe and Zn solubility. The HA greatly enhanced the maintenance in solution of Fe, in all the tested solutions, and Zn at pH 7.5. Mn mostly remained in solution in its inorganic forms. Plant growth experiments were carried out on both dicotyledonous plants (melons and soybean) and monocotytedonous Poaceae plants (ryegrass), due to the major difference in their Fe uptake mechanism. Plants grown in the absence of Fe exhibited severe Fe deficiency that could only partially be corrected with the addition of mineral Fe salts. The addition of HA or fulvic acid (FA) without addition of Fe, and Zn resulted in partial growth enhancement and correction of Fe deficiency, or none of the two, in the various experiments. This suggests that the growth enhancement effect observed in solutions containing Fe, Zn, and HS was related to the micronutrients rather than to phytohormones. However, the addition of Fe, Zn and either EDTA, HA or FA resulted in healthy, chlorophyll rich plants and enhanced growth, thereby providing evidence that improved Fe, and possibly Zn nutrition is a major mechanism of plant growth stimulation by HS. The use of the term hormone-like activity could be the result of the similarity of the physiological effects obtained in plants enjoying sufficient supply of Fe and Zn.     

Inhibitory action of dissolved humic substances on the growth of soil bacteria degrading DDT

Abstract

Dissolved humic acid (HA) and fulvic acid (FA) prepared from a Dando brown forest soil (Typic Dystrochrept) inhibited the growth of soil bacteria degrading DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) in the culture. The population of DDT-degrading Gram-variable rod Bll6 decreased by the application of both HA and FA, suggesting the presence of bactericidal effect. Such inhibitory effect was stronger for HA and resulted in a lower degrading activity of DDT in the culture of Bll6. No inhibitory effect was observed on the growth of DDT-degrading Bacillus sp. B75. The electron spin resonance spectra showed the presence of organic free radicals in both HA and FA. The relative concentration of the radicals was higher in HA. Storage of HA solution for 3 months at 4°C decreased the concentration of the radicals as well as the inhibitory action. The addition of catalase decreased the inhibitory effect of humic acid. It is suggested that a hydroxy radical, which is derived from free radicals of humic substances, is involved in the inhibition of bacterial growth and degradation of DDT.     

花绒寄甲对高温胁迫的适应能力及生理响应

商品化天敌昆虫在我国不同区域释放可能受到极端温度的影响和制约。花绒寄甲Dastarcus helophoroides（Fairmaire）是松墨天牛Monochamus alternatus Hope等蛀干害虫的重要天敌之一,具有良好的应用前景,但其在我国南方应用时控害效果常不稳定。以商品化花绒寄甲成虫为研究对象,并以常温25℃为对照,研究不同高温胁迫条件（33℃、36℃、39℃、42℃和45℃）对成虫的寿命、生殖、体内营养物质及抗氧化物活性的影响,旨在综合评价花绒寄甲成虫对高温胁迫的适应能力,为探讨其在我国南方松林中最佳释放时机、控害效果评价以及种群稳定性等方面提供科学依据。试验结果表明：高温胁迫（33℃~45℃）对花绒寄甲的成虫寿命具有显著影响,且随温度升高而显著缩短,据此可将高温区划分为致死高温区（42℃~45℃）、亚致死高温区（39℃~42℃）和高适温区（33℃~39℃）,其中花绒寄甲成虫在致死高温区内无法产卵,且卵块不能孵化;表明高温胁迫诱导花绒寄甲成虫产生强烈的抗逆代谢,消耗了大量营养物质,显著改变花绒寄甲成虫体内总糖、海藻糖和甘油三酯的含量;与此同时诱导花绒寄甲SOD、CAT活性的显著升高,POD活性的显著降低,与清除自由基有关。花绒寄甲成虫商品化种群耐受高温胁迫能力较弱,建议其在选择林间释放时间时,规避高温的潜在影响。应采用高适温区（33℃~39℃）进行驯化,以增强其成虫的耐高温及控害能力。     

核酸适配体技术在食品有害物检测中的研究进展

核酸适配体是一段可以特异性识别并结合靶分子的寡聚核苷酸片段,具有亲和力强、稳定性好、易于修饰等特点,已经广泛用于检测、分离纯化和医疗三大领域。基于核酸适配体技术的检测方法得到了迅速地发展,已经应用于小分子、蛋白质、细菌病毒等方面的检测。主要综述了核酸适配体检测食品中有害物的研究进展。     

土壤水分胁迫对红富士苹果叶片渗透调节特性的影响

在盆栽条件下,以10 a生长富2苹果为试材,设土壤相对含水量70%~80%(CK)、50%~60%(轻度水分胁迫)、40%~50%(中度水分胁迫)和30%~40%(重度水分胁迫)4个处理,应用P-V技术测定叶片的水分参数指标〔饱和含水时的最大渗透势(ψπ100)、膨压为0时的渗透势(ψπ0)、膨压为0时的相对含水量(RWC0)、相对渗透含水量(ROWC0)、束缚水含量(Va)、细胞最大弹性模量(εmax)〕和渗透调节相关物质(脯氨酸和可溶性糖)的含量,对不同程度土壤水分胁迫下红富士苹果的渗透调节特性和维持膨压的能力进行了综合分析。结果表明:随着土壤相对含水量的降低,红富士苹果叶片的ψπ100和ψπ0均呈逐渐降低趋势,且不同处理间的指标差异均达到了极显著水平(P0.01),其中,ψπ100与ψπ0的差值(ψπ100-ψπ0)在中度水分胁迫时最大(1.302 1)但与重度水分胁迫处理差异不显著;RWC0和ROWC0呈逐渐降低趋势,但均80%且显著CK,其中,RWC0在中度水分胁迫时最低且极显著其他处理(P0.01),ROWC0在重度水分胁迫时最低但与中度水分胁迫处理差异不显著(P0.05);Va呈逐渐增大趋势,其中,重度水分胁迫与中度水分胁迫处理差异不显著(P0.05),但二者均极显著轻度水分胁迫处理(P0.01);εmax呈逐渐降低趋势,且不同胁迫处理间的差异均达到了极显著水平(P0.01);叶片脯氨酸含量和可溶性糖含量均呈逐渐增加趋势,分别在中度、轻度水分胁迫时即与CK差异达到显著水平(P0.05)。当土壤相对含水量≥30%时,红富士苹果能够通过叶片的渗透调节来适应干旱环境胁迫。